Use PropertyPlaceholderConfigurer with List

Question

I am using PropertyPlaceholderConfigurer to map String values from properties file and it works ok.

My question is if I can set something the this in my property file: myList=A,B,C

And then map it to a list

@Value("${myList}")
private List<String> myList;

When I try that it puts all the values in one place of the list. Is there any way to tell it to break this to a list by ","?

Answer 1

Using Spring Expression language:

 @Value("#{'${myList}'.split(',')}") 
 private List<String> myList;

If myList=A,B,C in property file this will result in myList (in the code) with the values A, B and C

Answer 2

Take a look at sections 6.5.3 (Inline Lists) and 6.5.4 (Array Construction) on this link to Spring Expression Language Features.

From the link:

Lists can be expressed directly in an expression using {} notation.

// evaluates to a Java list containing the four numbers
List numbers = (List) parser.parseExpression("{1,2,3,4}").getValue(context); 

List listOfLists = (List) parser.parseExpression("{{'a','b'},{'x','y'}}").getValue(context);

{} by itself means an empty list. For performance reasons, if the list is itself entirely composed of fixed literals then a constant list is created to represent the expression, rather than building a new list on each evaluation.

I am not sure that this will work exactly like you would like it to with the @Value annotation in combination with the PropertyPlaceholderConfigurer, but it is worth a look.